1. Field of the Invention
The present invention relates to a light-sensitive material, more particularly, to a light-sensitive material using as an image forming substance an organic tellurium compound and containing colloidal particles of an element selected from the group consisting of gold, tellurium, germanium, palladium and platinum.
2. Description of the Prior Art
Light-sensitive materials have widely been used which comprise, as a light-sensitive substance or an image forming substance, a metal compound capable of giving a visible image consisting of stable metal crystallites by exposure and development.
Representative examples include those employed in photographic processes using silver halides as light-sensitive and image forming substances, details of which are described, for example, in C. E. K. Mees, The Theory of the Photographic Process, etc.
There are also known photographic processes utilizing physical development nuclei, in which a metal image is produced by exposing a light-sensitive layer to form development nuclei and then developing the nuclei in a solution containing silver or non-silver ions, as described, for example, in H. Jonker et al., Photographic Science and Engineering, 13, pages 1, 38 and 45 (1969); E. J. Delorenzo et al., ibid., 13, page 95 (1969); etc. These photographic processes, however, have disadvantages in that they are generally expensive due to the use of silver and involve complicated liquid processings even in the case where a non-silver metal is employed.
There are also known photographic processes in which no liquid processing is required and development is effected merely by heating. One material so processable is "Dry Silver" (trade name) sold by Minnesota Mining and Manufacturing Company, where silver halides are used as a light-sensitive substance and silver behenates as an image forming substance, and a visible image consisting of silver crystallites is obtained merely by heating after image-wise exposure. Such materials, however, are not free from the disadvantages of high cost and use of valuable resources due to the use of silver. As to details in "Dry Silver," see, for example, U.S. Pat. Nos. 3,152,903, 3,152,904 and 3,475,075.
As another photographic process of the heat developable type, there has recently been proposed a process using as a light-sensitive substance or as an image forming substance elemental organic compounds such as an organo-tellurium compound (e.g., a compound in which a tellurium atom is directly bonded to a carbon atom in an organic group), such as described in Japanese Pat. Application (OPI) No. 29,438/73 and German Offenlegungsshrift No. 2,233,868. The inventors previously proposed in Japanese Pat. application No. 14,330/74 a process using as an organo-tellurium compound a complex produced from a tellurium tetrahalogenide and an organic base. In these processes, no liquid processing is required and a visible image consisting of tellurium crystallites can be obtained by merely heating after image-wise exposure. In addition, they are advantageous because silver is not used.